1. Field of the Invention
This invention relates to improvements in electronic calculators having a printer, and more particularly to such calculators which are markedly improved in operability, easiness of use and economy.
2. Description of the Prior Art
In the conventional calculator systems, in order to cut off the recording paper, it was necessary to bring the paper over to the position of the paper cutter as shown in FIG. 1 by operating a specific paper feed key PF. This necessitated a shift of finger contact from the operation execution instructing key .sup.= and/or other keys to the key PF, and such requirement was an impediment to improvement of operability of the calculator system.
Also, in the conventional system, in order to stop the feed of paper at a desired point, the operator must release his finger hold on the key PF at a proper time by determining the feed with his own judgement. Therefore, wasteful feed would be made, and also skill was required for stopping the paper feed at the desired point.
Another serious defect of the conventional systems is that space feed of one line below the numerical sign "369.*" as shown in FIG. 2a would be made almost without exception, because there was provided no means capable of automatically or manually controlling feed for eliminating such space feed (see FIG. 2b). For lack of such means, the conventional systems could not overcome the problem of waste of paper when calculation and/or printing continues extensively and the difficulty involved in handling the lengthy printing paper. Still another and a most serious defect is that since the space feed time is absolutely required when the calculator is operated over a certain fixed period of time, it may follow that the printing speed can no longer cover the key operating speed, making it unable to perform operation or printing any longer. In order to overcome such problem, it has been attempted to inhibit key input when the calculator is performing an operation or printing, or to temporarily store the key signal in a memory (see FIG. 3A). However, if the operation is continued to an extent that exceeds memory capacity, there would inevitably come a situation where operation or printing is no longer possible to carry on. In order to allow the operation to follow the rapid key touching pattern such as shown in FIG. 3B, it is best to eliminate any space feed.